Sorry about the shot's not being that fantastic, my camera and my skills with it just are not good enough, but hopefully you can make it out enough? This is the base, with the closest that I could find to a vague part of a P, though there appears to be surface flakes of glass lost around the outer edge of the pontil mark so if a P was there, it would be gone with the missing glass? I'm not sure about the mark to the side of the pontil mark as it's totally filled in on the surface, like you get with hand signed items but lighter and isn't impressed, it may just be a graze? But to me, it does also resemble the top of a letter p so could it be the 'D' part of that letter?